I thought the sound barrier existed because of the wind itself. The sound barrier is the point at which the object in question travels faster than the speed at which the sound can travel through said medium. But if all of the winds on Neptune are traveling at those speeds, then wouldn't the sound that they make thereby be traveling within them? So they wouldn't be breaking any barrier, because they are traveling within their barrier?

you would just hear a really loud wind sound similar to large gust from hurricanes but in this case it would be much faster and louder as for what it would look like it depends on what the atmosphere is made up of since it's blue I think it's methane(could be wrong) if it is methane it would give the wind a slight distortion effect similar to looking through water

you're not dumb its kind of like that to be fair, if for example a jet flies past you and its going faster than the speed of sound it passes silently then you hear a big crash as the sound follows behind it hope that helps!

Didn't I read it rains diamonds on neptune? Does that mean it is entirely possible that during a storm there are diamonds flying through the air breaking the sound barrier? And I thought Venus was scary hot damn.